A number of different electro-mechanical pulse generators are disclosed in U.S. Pat. No. 5,380,965, U.S. Pat. No. 6,972,306, U.S. Pat. No. 6,943,308, DE 3025514 and DK-A-168,258. Most of these electro-mechanical pulse generators are relatively complicated with a large number of parts and have no self-cleaning properties. The electro-mechanical pulse generator disclosed in DE 3025514 lacks a mechanism to prevent rebound of a displaceable contact portion during its travel between two opposing stationary electrical contacts.